Gaseous electric discharge lamp



Feb.;ll, 1936. A.IR UITTENAUVER EI'AL 2,

GASEOUS ELECTRIC, DISCHARGE LAMP Filed Aug. 14, 1955 INVENTORS ORN'EYUNITED STATES PATENT OFFICE 2,030,403 GASEOUS ELECTRIC DISCHARGE LAMPAlfred Biittenauer, Berlin-Halensee, and Otto Fritze, Berlin, Germany,assignors to General Electric Company, a corporation of New YorkApplication August 14. 1935, serial No. 36,190

In Germany August 25, 1934 i 1 Claim.

The present invention relates to gaseous electric discharge lampsgenerally and more particularly the invention relates to mercury vaporlamps having a fluorescent material associated therewith which materialtransforms rays of certain wave length emitted by the gaseous electricdischarge in the lamp into rays of other wave length to complement andsupplement the light emitted by said discharge.

Certain types of fluorescent materials while emitting light of a colorcomplementary to the light "emitted by the mercury vapor discharge arenot fully excited by the ultra-violet light emitted by said dischargeand hence the intensity of the fluorescent light is too weak tocomplement the visible light emitted by said discharge. Such afluorescent material is rhodamin, for example,

which emits red light.

The object of the present invention is to provide a lamp of the abovetype which is more eflicient and more effective than those now known inthe art. Still further objects and advantages attaching to the deviceand to its use and operation will be apparent to those skilled in theart from the following particular description.

The present invention attains its object by interposing between thegaseous electric discharge in the lamp and the body of rhodamin a bodyof another fluorescent material which transforms substantially all ofthe effective ultra-violet rays emitted by the said mercury vapordischarge into rays which fully excite the rhodamin. The red raysemitted by the rhodamin are then of high intensity to complement thevisible light emitted by the discharge.

In the drawing accompanying and forming part of this specification anembodiment of the invention is shown in a side elevational, partlysectional view.

Referring to the drawing the lamp comprises an elongated, tubularcontainer I having electrodes 2 and 3 sealed into the ends thereof and agaseous atmosphere therein comprising a starting gas, such as argon, anda quantity 5 of vaporizable material, such as mercury, the

vapor of which is light emitting during the operation of the device.Said electrodes 2 and 3 are sintered mixtures of electron emittingmaterial, such as barium oxide, and high melting point material, such astungsten, are electron emitting when at an elevated temperature and areheated to the operating, electron emitting temperature thereof by thevoltage drop therethrough. When desired, electrodes are used.

thereat and current flow cold, sheet metal Said container I has acoating of fluorescent material, such as zinc silicate or zinc sulfide,which transforms the ultra-violet light emitted by the mercury vapordischarge between said electrodes 2 and 3 into yellow or green colored 5light, respectively. The coating 4 is' applied to the inner surface ofsaid container l by methods now known in the art, such as by heating thecontainer l to the softening temperature and propelling particles of thefluorescent-material toward the softened inner surface of said containerI so that the particles are partially em bedded in said surface, asdisclosed in co-pending application, Serial Number 758,514, filedDecember 20, 1934 or by partially embedding the fluo- 5 rescent materialin a layer of light transmitting enamel applied to the inner surface ofsaid container I and having a lower softening temperature than saidcontainer l, as disclosed in 00- pending application Serial Number758,028, filed December 18, 1934. A coating 6 of material which isstrongly excited by the light emitted by the fluorescent coating 4 isapplied to the outer surface of said container I. Said coating 6consists of rhodamin, for example, which when ex- 5 cited by the lightemitted by the coating 4 emits red rays of sufficient intensity tocomplement the spectrum of the light emitted by the mercury vapordischarge in said lamp.

When the lamp is to be used for illumination the thickness of saidcoatings 4 and 6 is such that substantially all the'visible lightemitted by the luminous discharge is transmitted thereby. The coating4should be of sufficient thickness to emitted by the discharge intovisible light. When the lamp is to be used for advertising purposes itis effective to apply both the coating 4 and the coating 6 on the outersurface of the container l the coating 4 completely covering said sur- 4face and the coating 6 being applied to said coating 4 in the form of adesign, or a character, or symbol. In this case {the container I must bemade of an ultra-violet transmitting material, such as quartz, and thecoating 4 is preferably of such thickness that only the yellow or greenlines emitted by the discharge are transmitted thereby. The lamp thenhas glowing red char- 0 acters on a glowing yellow or green surface andthose skilled in-the art without departing from the broad spirit andscope of the invention. What we claim as new and desire to secure byLetters Patent of the United States, is:-

A gaseous electric discharge lamp comprising a; container, electrodessealed therein, a gaseous atmosphere therein capable of emitting visiblelight and ultra-violet light when excited by an electric dischargebetween said electrodes, 2. body 7 of luminescent material which isweakly excited 2,080,403 and in its use and operation may be made by bythe rays emitted by"said discharge and another body of material whichtransforms the ultra-violet rays emitted by said discharge into visiblelight which strongly excites the material of said first named body andcauses it to emit first named body and by said discharge, said lastnamed body being interposed between said first named body and saiddischarge. I

ALFRED RfiI'IENAUER.

